A Beth Lumsden double saw the Magpies pick up all three points at the Stadium of Light on Sunday, but it was a team display which was required for the victory.
Watt picked up the team's Players' Player of the Year award last season and has now started two of the club's last three games, including the Women's League Cup tie against Everton Women earlier this month.
Now plying her trade at right-back under Becky Langley, Watt was left smiling from ear-to-ear after her contribution to the historic win on Sunday.
"This is the best feeling in football," Watt admitted. "To have made the starting line-up, played 90 minutes and picked up three points against Sunderland, the day really couldn't have gone much better.
"It was such a big occasion, but one I believe we all rose to. We brought passion to our game and I thought we were the better team over 90 minutes.
"We were excellent at winning the first and second balls throughout the game and that's what we pride ourselves on."
Playing away from home against their local rivals and in front of a record Championship crowd was always going to present its unique challenges for United.
However, after a solid week of preparation, Watt and her team-mates controlled the afternoon and ensured the game was played at their pace, with Sunderland the team forced to adapt on their home pitch.
Watt added: "I thought we brought the game to them from the first minute.
"We were aggressive in our tackles and showed everyone that we weren't willing to leave without three points."
Before Sunday's victory, it may have seemed like a frustrating season for Watt from the outside looking in, but she explained that couldn't have been further from the truth.
United's number five kept her head down to ensure she gave manager Langley a selection dilemma ahead of each game.
And she said: "I just want to do my job whenever I step out onto the pitch, whether that be starting or coming on as a substitute during the game.
"Hopefully, I can play my role well and continue to give Becky something to think about.
"We play football for moments like this - getting to celebrate derby wins with our fans is the best feeling."
While the 15,387 attendance at the Stadium of Light was a new record for the Women's Championship - beating the previous highest crowd of 11,137, set when Sheffield United Women played London City Lionesses in November 2022, Newcastle will hope to beat that when they take on Southampton Women at St. James' Park next month.
A priority window for Newcastle United Women season ticket holders for the game on Sunday, 17th November is now open.
Meanwhile, the Lasses are at Kingston Park this weekend when they take on Charlton Women. Kick-off is at 12 noon and tickets are on sale here.